U.S. Pat. No. 4,672,501 entitled "Circuit Breaker and Protective Relay Unit" describes the use of a digital circuit interrupter employing a microprocessor in combination with ROM and RAM memory elements to provide both relaying as well as protection function to an electrical distribution system. The associated electronic trip unit is contained on printed circuit cards that are positioned within a recess in the digital circuit interrupter cover.
U.S. Pat. No. 4,870,531 entitled "Circuit Breaker with Removable Display and Keypad" describes a digital display and keypad used to select circuit breaker trip settings and allows the settings to be viewed.
U.S. patent application Ser. No. 08/239,822 entitled "Digital Circuit Interrupter with Multiple Accessory Function" describes an integrated circuit breaker having several accessory functions along with automatic overcurrent protection, which allows selection between the various accessory functions in different combinations. Separate switches arranged on the circuit interrupter trip unit allow factory as well as field selection of the accessory function combinations. The selected accessory units are inserted in the circuit interrupter cover adjacent to the trip unit.
U.S. patent application Ser. No. 08/248,908 entitled "Bell Alarm and Lock-out Accessory for a Circuit Interrupter" describes one such accessory unit used within the aforementioned "Circuit Interrupter with Multiple Accessory Function".
One purpose of the instant invention is to provide an arrangement whereby several accessory units can be electrically-connected with the circuit breaker trip unit. An additional purpose is to interlock the circuit breaker trip unit with the circuit breaker operating mechanism. A further purpose of the invention is to insure that the accessory units are properly interconnected within the trip unit circuit.